Ultra Filtration units contain semi-permeable membranes to remove suspended solids, high molecular weight solutes and even low level oil contamination from water. The water to be cleaned is forced under pressure through the membrane whereby the contaminants are retained on the membrane surface allowing the low molecular weight solutes (minerals etc.) to pass through.
This separation technique is typically used to remove heavy weight organics in waste water streams or to purify clean water.
The system may operate as a “cross-flow” or “dead end”. In either case the membrane will become fouled and will require back-washing to remove the debris to drain.
Backwashing the membrane is accomplished by reversing the flow through the membrane via a high pressure high flow for a short interval and discharging the waste to drain. The membrane will be backwashed using clean water and chemical cleaning agents may be applied.
The backwash may be initiated by time, flow rate or pressure drop.